Reliance on petroleum-derived fuels has depleted the supply of natural resources and has required increased reliance on imported gasoline and diesel products. In addition, the burning of petroleum-based fuels has increased the amount of greenhouse gasses (e.g., carbon dioxide and methane) in the atmosphere that is contributing to the gradual warming of the earth's climate.
Fuels, such as biodiesel, that are made from animal or vegetable products burn cleaner than petroleum-derived fuels and do not produce a net increase in greenhouse gases. Furthermore, they are a sustainable energy source and have the potential to reduce the United States' reliance on imported petroleum-based products. However, there is a concern that using land to produce fuel crops rather than food crops will contribute to world hunger.
Fatty acids are the principal component of cell membranes and are used by nearly all organisms as a primary source of energy storage. Fatty alcohols are the reduction products of fatty acids and, like fatty acids, can be produced enzymatically by cultured cells. Fatty alcohols can be reacted with acids to form ester compositions similar to those present in biodiesel fuel, or reduced to form kerosene-like compositions, or hydrocarbon compositions similar to petrodiesel. Enzymes that convert fatty acyl-thioester substrates (e.g., fatty acyl-CoA or fatty acyl-ACP) to fatty alcohols are commonly referred to as fatty alcohol forming acyl-CoA reductases or fatty acyl reductases (“FARs”).
PCT Publication No. WO 2007/136762 discloses genetically engineered microorganisms for the production of fatty acid derivatives and methods of their use.
U.S. Pat. No. 5,370,996 and Metz et al., 2000, Plant Physiology 122:635-644 disclose isolation and characterization of a fatty acyl reductase (FAR) enzyme from the desert shrub Simmondsia chinensis, more commonly known as jojoba.
Moto et al., 2003, Proc. Nat'l Acad. Sci. USA 100(16):9156-9161 discloses the isolation and characterization of a FAR enzyme from the silk moth Bombyx mori. 
Reiser et al., 1997, J. Bacteriol. 179(9):2969-2975 discloses the isolation and characterization of a fatty acyl CoA reductase enzyme from the wax ester producing bacterium Acinetobacter calcoaceticus that reduces a fatty acyl-CoA substrate with chain lengths from C14 to C22 to the corresponding fatty aldehyde, requiring a dehydrogenase enzyme for conversion of the fatty aldehyde to the fatty alcohol.
In theory, these FAR enzymes could be expressed in heterologous hosts as a means of producing a non-petroleum-based, renewable source of fatty alcohol or derivative compositions for use in biofuels. However, when expressed in heterologous hosts such as E. coli and yeast, the yields of fatty alcohols obtained are insufficient for certain applications. In addition, at most, only a small fraction of fatty alcohols produced are secreted by the microorganisms, increasing substantially the cost of purification.
Accordingly, there is a need in the art for enzymes such as FAR enzymes that can be used efficiently to produce fatty alcohols for use in industrial applications such as but not limited to applications in the chemical industry (e.g., household detergents, including laundry detergents in liquid and powder form, hard surface cleaners, dishwashing liquids, and the like; lubricants and solvents; industrial cleaners; and surfactants), in the food industry, in the personal care industry (e.g., in soaps, cosmetics, shampoos, and gels), in the medical industry, and in the fuels industry (e.g., in diesel fuels).